The phrase filled with cream, covered in chocolate frosting, and dusted with sprinkles incorrectly describes you.

To fix the dangler, you could revise the sentence as follows:

Filled with cream, covered in chocolate frosting, and dusted with sprinkles, this cupcake is to be enjoyed.

Here, the phrase filled with cream, covered in chocolate frosting, and dusted with sprinkles correctly describes this cupcake.

Watching has no subject. Cell phones don’t watch.

To fix the dangler, you could revise the sentence as follows:

When watching a theater performance, audience members should silence their cell phones.

Here, it is the audience members who are watching.

As a teacher incorrectly describes patience. 

To fix the dangler, you could revise the sentence as follows:

As a teacher, you must be patient.

Here, as a teacher describes you.

Driving down the highway correctly refers to the subject doing the driving: we.

To climb has no subject. Sacrifices do not climb. 

To fix the dangler, you might revise the sentence as follows:

You must make sacrifices to climb the corporate ladder.

Here, you is the subject that climbs the corporate ladder.